There have been some past rumblings on the internet about a capacitor being installed backwards in Apple’s Macintosh LC III. The LC III was a “pizza box” Mac model produced from early 1993 to early 1994, mainly targeted at the education market. It also manifested as various consumer Performa models: the 450, 460, 466, and 467. Clearly, Apple never initiated a huge recall of the LC III, so I think there is some skepticism in the community about this whole issue. Let’s look at the situation in more detail and understand the circuit. Did Apple actually make a mistake?
I participated in the discussion thread at the first link over a decade ago, but I never had a machine to look at with my own eyes until now. I recently bought a Performa 450 complete with its original leaky capacitors, and I have several other machines in the same form factor. Let’s check everything out!
Here’s the affected section of the board before I removed the original capacitors. You can see that all three of these caps (C19, C21, and C22) have their negative side pointing upward, matching the PCB silkscreen that has the + sign at the bottom.
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